Not short and sweet, but short and professional. If there are unpleasant truths, share them in one-on-one meeting (exit interview) with HR or a senior level person that you trust. And even then, be careful how you phrase it in the event you need them as a reference in the future.

When it comes time to write a 2-weeks notice to get out of a horrible job, do you write the unpleasant truths about why you're leaving or do you keep it short and sweet?

Short and sweet. If you're granted an exit interview, that would be an appropriate time to address the reasons you're leaving - professionally.

Don't burn a bridge unless you're completely sure that you will never need to cross it again.

That said, I find writing the version you'd really like to submit can be very therapeutic. About 12 years ago, I quit a very toxic company and the night before I resigned, I had dinner with a friend where we talked about what I really wanted to say to my employer. Once I got it out of my system, my actual letter of resignation was boilerplate.

How I was told to handle it is you say "It is with regret that I am submitting my resignation, effective May 1st, or earlier as you may require." You might add "Please advise the exit process so that we both have the smoothest transition possible" or something to that affect.

Don't tell them where you're going or what you're doing. It's none of their business and can bite you in the arse. If there are things you feel you really must share (and really, will it be helpful or just make you feel better for the ragequit?) then do it as part of the exit interview, NOT in writing.

__________________"Traveling - It leaves you speechless, then turns you into a storyteller. ~ Ibn Battuta

You NEVER know when someone that you work with currently might come around on the Karma train down the road in your career or who might know who. Remember that and be careful what you say and put into writing. Not your job to fix the company that you are leaving.

ETA: And having just read your last post, I REALLY REALLY advise you to keep your mouth shut. It is clear that there is a hell of a lot going on that you are not privy to. Don't shoot yourself in the foot.

Some back story may be relevant here: I'm a correctional officer in a facility that mostly houses juveniles. One of the juveniles reported some sexual misconduct between an employee and the minor. I reported it, and ever since I've been getting retaliated against by my superiors. My coworkers are behind me because this CO had also racked up 6 sexual harassment allegations from current and former coworkers. For whatever reason, our building management protects this girl and nothing has ever come of her misconduct.
On Wednesday I was given a performance eval and I was told, very clearly, to quit paying attention to what others are doing, even if wrong or illegal. and that was my final straw.

ETA: And having just read your last post, I REALLY REALLY advise you to keep your mouth shut. It is clear that there is a hell of a lot going on that you are not privy to. Don't shoot yourself in the foot.

Did you read a different post than I did? There is absolutely a moral imperative to report something that involves sexual misconduct with a minor.

Do the professional exit but before you do gather all the doc you can and then get this person thrown in jail. After you're out of there. I don't know who you go to outside your direct chain of command, but there has to be SOMEONE who cares about the well-being of these children.

__________________"Traveling - It leaves you speechless, then turns you into a storyteller. ~ Ibn Battuta

Depending on your state laws and your profession, you may be required by law to report it or be held liable as well. You may want to check that out. You don't have to report the misconduct to your employer, if it borderlines on misconduct the authorities may be your only recourse.

I DID report it and that's where all this retaliation is coming from. Although I was promised that my name would not be revealed during the investigation, an email was sent with my first name in it and it all went to hell from there.

I think my letter is just going to cite "ethical concerns" and acknowledge that I am available for an exit interview with the company.

Also, I've gotten a couple of PMs about the post I deleted but it still QFPed. I deleted that post immediately after the response that said "keep your mouth shut" in a knee-jerk reaction. I don't mind that it's still QFPed.